<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        // 原生AJAX
        const xhr = new XMLHttpRequest();
        xhr.open("GET", "http://www.liulongbin.top:3006/api/getbooks");
        xhr.send();
        xhr.onreadystatechange = function () {
            if (xhr.readyState === 4) {
                if (xhr.status >= 200 && xhr.status < 300) {
                    return console.log(xhr.responseText);
                } else {
                    console.error(xhr.status);
                }
            }
        }
        // 使用Promise包装
        const p = new Promise((resolve, reject) => {
            const xhr = new XMLHttpRequest();
            xhr.open("GET", "http://www.liulongbin.top:3006/api/getbooks");
            xhr.send();
            xhr.onreadystatechange = () => {
                if (xhr.readyState === 4) {
                    if (xhr.status >= 200 && xhr.status < 300) {
                        // return console.log(xhr.responseText);
                        resolve(xhr.responseText)
                    } else {
                        // console.error(xhr.status);
                        reject(xhr.status)
                    }
                }
            }
        }).then((value) => {
            console.log(value);
        }).catch((reason) => {
            console.error(reason);
        })
    </script>

</body>

</html>